<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .box {
        position: relative;
        width: 600px;
        height: 600px;
        background-color: #ccc;
        .a1 {
          position: absolute;
          width: 200px;
          height: 200px;
          border-radius: 50%;
          background-color: black;
          margin-left: 200px;
          margin-top: 100px;
        }
        .a2 {
          position: absolute;
          width: 200px;
          height: 200px;
          border-radius: 50%;
          background-color: black;
          margin-left: 100px;
          margin-top: 200px;
        }
        .a3 {
          position: absolute;
          width: 200px;
          height: 200px;
          border-radius: 50%;
          background-color: black;
          margin-left: 300px;
          margin-top: 200px;
        }
        .b1 {
          position: absolute;
          border-top: solid 100px transparent;
          border-right: solid 100px transparent;
          border-left: solid 100px transparent;
          border-bottom: solid 200px black;
          margin-left: 200px;
          margin-top: 200px;
        }
      }
    </style>
  </head>
  <body>
    <div class="box">
      <div class="a1"></div>
      <div class="a2"></div>
      <div class="a3"></div>
      <div class="b1"></div>
    </div>
  </body>
</html>
